Distributed recognition of natural songs by European starlings

Individual vocal recognition behaviors in songbirds provide an excellent framework for the investigation of comparative psychological and neurobiological mechanisms that support the perception and cognition of complex acoustic communication signals. To this end, the complex songs of European starlings have been studied extensively. Yet, several basic parameters of starling individual vocal recognition have not been assessed. Here we investigate the temporal extent of song information acquired by starlings during vocal recognition learning. We trained two groups of starlings using standard operant conditioning techniques to recognize several songs from two conspecific male singers. In the first experiment we tested their ability to maintain accurate recognition when presented with (1) random sequences of 1–12 motifs (stereotyped song components) drawn from the training songs, and (2) 0.1–12-s excerpts of continuous song drawn from the training songs. We found that song recognition improved monotonically as more vocal material is provided. In the second experiment, we systematically substituted continuous, varying length regions of white noise for portions of the training songs and again examined recognition accuracy. Recognition remained above chance levels for all noise substitutions tested (up to 91% of the training stimulus) although all but the smallest substitutions led to some decrement in song recognition. Overall, above chance recognition could be obtained with surprisingly few motifs, short excerpts of song, and in the absence of large portions of the training songs. These results suggest that starlings acquire a representation of song during individual vocal recognition learning that is robust to perturbations and distributed broadly over large portions of these complex acoustic sequences.     

Stimulus-dependent flexibility in non-human auditory pitch processing

Songbirds and humans share many parallels in vocal learning and auditory sequence processing. However, the two groups differ notably in their abilities to recognize acoustic sequences shifted in absolute pitch (pitch height). Whereas humans maintain accurate recognition of words or melodies over large pitch height changes, songbirds are comparatively much poorer at recognizing pitch-shifted tone sequences. This apparent disparity may reflect fundamental differences in the neural mechanisms underlying the representation of sound in songbirds. Alternatively, because non-human studies have used sine-tone stimuli almost exclusively, tolerance to pitch height changes in the context of natural signals may be underestimated. Here, we show that European starlings, a species of songbird, can maintain accurate recognition of the songs of other starlings when the pitch of those songs is shifted by as much as ±40%. We observed accurate recognition even for songs pitch-shifted well outside the range of frequencies used during training, and even though much smaller pitch shifts in conspecific songs are easily detected. With similar training using human piano melodies, recognition of the pitch-shifted melodies is very limited. These results demonstrate that non-human pitch processing is more flexible than previously thought and that the flexibility in pitch processing strategy is stimulus dependent.     

Auditory temporal pattern learning by songbirds using maximal stimulus diversity and minimal repetition

The sequential patterning of complex acoustic elements is a salient feature of bird song and other forms of vocal communication. For European starlings (Sturnus vulgaris), a songbird species, individual vocal recognition is improved when the temporal organization of song components (called motifs) follows the normal patterns of each singer. This sensitivity to natural motif sequences may underlie observations that starlings can also learn more complex, unnatural motif patterns. Alternatively, it has been proposed that the apparent acquisition of abstract motif patterning rules instead reflects idiosyncrasies of the training conditions used in prior experiments. That is, that motif patterns are learned not by recognizing differences in temporal structures between patterns, but by identifying serendipitous features (e.g., acoustical cues) in the small sets of training and testing stimuli used. Here, we investigate this possibility, by asking whether starlings can learn to discriminate between two arbitrary motif patterns, when unique examples of each pattern are presented on every trial. Our results demonstrate that abstract motif patterning rules can be acquired from trial-unique stimuli and suggest that such training leads to better pattern generalization compared with training with much smaller stimulus subsets.     

Five-month-old infant recall and utilization of temporal organization

The ability of 5-month-old infants to recall temporal information and utilize temporal organization was investigated in two experiments. Infants were trained to fixate a hierarchically structured or an unstructured sequence of stimuli which appeared in four spatial positions. In the first study, the number of infants who demonstrated correct recall through the third serial position of a sequence was significantly better then would occur by chance. In the second study, infants given structured sequences showed a significant increase in the number of correct fixations across trials, and they recalled across serial positions better in structured sequences. Also, accuracy of recall in both studies for the middle serial positions was related to hierarchical organization following 8-unit structured sequence training but was at chance level following unstructured sequence training. Results of both studies were interpreted within a temporal organizational framework: Infants appear to utilize organization within sequences of information.     

Hearing by eye

Recent work on integration of auditory and visual information during speech perception has indicated that adults are surprisingly good at, and rely extensively on, lip reading. The conceptual status of lip read information is of interest: such information is at the same time both visual and phonological. Three experiments investigated the nature of short term coding of lip read information in hearing subjects. The first experiment used asynchronous visual and auditory information and showed that a subject's ability to repeat words, when heard speech lagged lip movements, was unaffected by the lag duration, both quantitatively and qualitatively. This suggests that lip read information is immediately recoded into a durable code. An experiment on serial recall of lip read items showed a serial position curve containing a recency effect (characteristic of auditory but not visual input). It was then shown that an auditory suffix diminishes the recency effect obtained with lip read stimuli. These results are consistent with the hypothesis that seen speech, that is not heard, is encoded into a durable code which has some shared properties with heard speech. The results of the serial recall experiments are inconsistent with interpretations of the recency and suffix effects in terms of precategorical acoustic storage, for they demonstrate that recency and suffix effects can be supra-modal.     

The unimportance of explicit spatial information in serial recall of visually presented lists

The superiority of auditory over visual presentation in short-term serial recall may be due to the fact that typically only temporal cues to order have been provided in the two modalities. Auditory information is usually ordered along a temporal continuum, whereas visual information is ordered spatially, as well. It is therefore possible that recall following visual presentation may benefit from spatial cues to order. Subjects were tested for serial recall of letter-sequences presented visually either with or without explicit spatial cues to order. No effect of any kind was found, a result which suggests (a) that spatial information is not utilized when it is redundant with temporal information and (b) that the auditory-visual difference would not be modified by the presence of explicit spatial cues to order.     

Relative pitch perception in the European starling (Sturnus vulgaris): further evidence for an elusive phenomenon

Relative pitch perception in animals has been difficult to demonstrate. This failing is due in part to stimulus sets that make an absolute pitch solution viable. In Experiment 1, starlings failed to acquire a discrimination that could be solved only on the basis of relative pitch. In Experiment 2, starlings were trained on a smaller set of pitch patterns, for which both absolute and relative pitch solutions were available, then tested with three series of unreinforced probe stimuli. Series 1 assessed stimulus control by absolute pitch. In Series 2, absolute pitch cues dictated one response, and relative pitch cues dictated a different response. Results indicate that starlings extract relative pitch from artificial pitch patterns only after acquiring a discrimination that permits both absolute and relative pitch solutions. Results are discussed in terms of the relative salience of absolute and relative pitch.     

Encoding location and serial order in auditory working memory: evidence for separable processes

In this study, we investigated the interactions between temporal and spatial information in auditory working memory. In two experiments, participants were presented with sequences of sounds originating from different locations in space and were then asked to recall either their position or their serial order. In Experiment 1, attention during encoding was manipulated by contrasting 'pure' blocks (i.e., location-only or serial-order-only trials) to 'mixed' blocks (i.e., different percentages of spatial and serial-order trials). In Experiment 2, 'pure' blocks were contrasted to blocks in which spatial and serial-order trials were intermixed with a third task requiring a semantic categorization of sounds. Results from both experiments showed that, whereas serial-order recall is linearly affected by the simultaneous encoding of a concurrent feature, the recall of position is mostly unaffected by concurrent feature encoding. Contrastingly, overall performance level was lower for spatial recall than serial recall. We concluded that serial order and location of items appear to be independently encoded in auditory working memory. Serial order is easier to recall, but strongly affected by the processing of concurrent item dimensions, while item location is more difficult to recall, but relatively automatic, as shown by its strong resistance to interfering dimensions in encoding.     

A tactile suffix effect

Evidence for a representational tactile memory was obtained from a tactile analogue of the auditory suffix effect. In two experiments, a short sequence of tactile stimuli applied to the fingers was followed by an acoustic (control) or tactile (suffix) recall signal. The serial position curves for the two conditions were compared. They revealed similar and strong primacy effects, but recall of the last few stimuli was higher in the control condition. This terminal control advantage was attributed to the retention of raw tactile information.     

Perceptual organization and precategorical acoustic storage

Current views of precategorical acoustic storage (PAS) have been largely based on differences in the level of recall of terminal list items as a function of input modality and on experiments in which various types of suffixes are added to unstructured auditory lists. Experiments with grouped lists reveal that PAS can make a far more extensive contribution to serial recall. A series of four experiments investigated grouping effects in relation to existing accounts of consolidation, attentional selection, and auditory masking in PAS. Grouping effects obtained with very brief intralist pauses were inconsistent with the consolidation and masking hypotheses. Contrary to the attentional hypothesis, nontemporal grouping by voice or by spatial location was found to be as effective as grouping by extended pauses. When nontemporal methods of grouping were combined with intralist pauses, the two sets of grouping cues were no better than one, suggesting that list segmentation by pauses and by item attributes must be explained in terms of a single process. These results are discussed in the context of previous research that implies the existence of an auditory store with a capacity greater than previously attributed to PAS. Existing data on modality and suffix effects are seen as specific instances of a more general relation between the structure of spoken sequences and their subsequent recall.     

Recency and the modality effect in immediate ordered recall

In immediate ordered recall, recency is the improved recall of the last item of a presentation, and the modality effect is the advantage for an acoustic presentation over a subvocalized visual presentation, primarily occurring at the last serial position. Experiment 1 tested grouped presentations. There was a modality effect for the first item of the last group, even though that item was at the third-to-last or fourth-to-last serial position. In Experiment 2, for vocalized presentations of syllables ending in a, recency was larger for staccato speech than legato speech; for subvocalized presentations, there was a substantial recency for the legato style. In Experiment 3, recency was larger for a set of syllables ending in ATE than for a set of syllables ending in AME. These results suggest that recency cannot be explained by the existence of a fixed-capacity store, auxiliary to the auditory short-term store, that retains only some types of presentations. It is suggested instead that recency might reflect an auxiliary method of using the information in the auditory short-term store.     

Identifying the mechanisms underpinning recognition of structured sequences of action

We present three experiments to identify the specific information sources that skilled participants use to make recognition judgements when presented with dynamic, structured stimuli. A group of less skilled participants acted as controls. In all experiments, participants were presented with filmed stimuli containing structured action sequences. In a subsequent recognition phase, participants were presented with new and previously seen stimuli and were required to make judgements as to whether or not each sequence had been presented earlier (or were edited versions of earlier sequences). In Experiment 1, skilled participants demonstrated superior sensitivity in recognition when viewing dynamic clips compared with static images and clips where the frames were presented in a nonsequential, randomized manner, implicating the importance of motion information when identifying familiar or unfamiliar sequences. In Experiment 2, we presented normal and mirror-reversed sequences in order to distort access to absolute motion information. Skilled participants demonstrated superior recognition sensitivity, but no significant differences were observed across viewing conditions, leading to the suggestion that skilled participants are more likely to extract relative rather than absolute motion when making such judgements. In Experiment 3, we manipulated relative motion information by occluding several display features for the duration of each film sequence. A significant decrement in performance was reported when centrally located features were occluded compared to those located in more peripheral positions. Findings indicate that skilled participants are particularly sensitive to relative motion information when attempting to identify familiarity in dynamic, visual displays involving interaction between numerous features.     

Identifying the mechanisms underpinning recognition of structured sequences of action

We present three experiments to identify the specific information sources that skilled participants use to make recognition judgements when presented with dynamic, structured stimuli. A group of less skilled participants acted as controls. In all experiments, participants were presented with filmed stimuli containing structured action sequences. In a subsequent recognition phase, participants were presented with new and previously seen stimuli and were required to make judgements as to whether or not each sequence had been presented earlier (or were edited versions of earlier sequences). In Experiment 1, skilled participants demonstrated superior sensitivity in recognition when viewing dynamic clips compared with static images and clips where the frames were presented in a nonsequential, randomized manner, implicating the importance of motion information when identifying familiar or unfamiliar sequences. In Experiment 2, we presented normal and mirror-reversed sequences in order to distort access to absolute motion information. Skilled participants demonstrated superior recognition sensitivity, but no significant differences were observed across viewing conditions, leading to the suggestion that skilled participants are more likely to extract relative rather than absolute motion when making such judgements. In Experiment 3, we manipulated relative motion information by occluding several display features for the duration of each film sequence. A significant decrement in performance was reported when centrally located features were occluded compared to those located in more peripheral positions. Findings indicate that skilled participants are particularly sensitive to relative motion information when attempting to identify familiarity in dynamic, visual displays involving interaction between numerous features.     

Semantic and acoustic processing in free and cued recall by educable mentally retarded adolescents

The abilities of educable mentally retarded adolescents to encode and retrieve words with semantic and acoustic cues were investigated in a free and cued recall task. On each of three trial blocks, seven groups of subjects were presented 20 unrelated stimulus words. Groups received either semantic, acoustic, or no encoding cues along with the stimuli. Free recall was requested from all subjects, followed immediately by a second period of either free recall or cued recall with the semantic or acoustic cues. Semantic cues were most effective when presented both at encoding and retrieval. The subjects were unable to use acoustic information as effective retrieval aids. Results were discussed in terms of encoding dimension dominance and mediational deficiencies.     

Part-list cuing and the dynamics of false recall

False recall of an unpresented critical word after studying its semantic associates can be reduced substantially if the strongest and earliest-studied associates are presented as part-list cues during testing (Kimball & Bjork, 2002). To disentangle episodic and semantic contributions to this decline in false recall, we factorially manipulated the cues’ serial position and their strength of association to the critical word. Presenting cues comprising words that had been studied early in a list produced a greater reduction in false recall than did presenting words studied late in the list, independent of the cues’ associative strength, but only when recall of the cues themselves was prohibited. When recall of the cues was permitted, neither early-studied nor late-studied cues decreased false recall reliably, relative to uncued lists. The findings suggest that critical words and early-studied words share a similar fate during recall, owing to selective episodic strengthening of their associations during study.     

Part—set cuing of order information: Implications for associative theories of serial order memory

In three experiments, the effect of cuing, at the point of test, on memory for order and/or position was investigated. Experiment 1 used a partial reconstruction of order task to demonstrate a mnemonic benefit of part-set cuing at the time of test; this result is used to argue that people may commonly use interitem associative information, rather than just position information, to help them remember serial order. Experiment 2 replicated these findings and simultaneously demonstrated the mnemonic detriment that part-set cuing typically produces in free recall. Experiment 3 showed that cues presented at test will either help or hinder reconstruction of order, depending on whether those cues are consistent or inconsistent with the original presentation order. The results of all three experiments are discussed within the framework of position and associative theories of serial order memory.     

Dissociable lexical and phonological influences on serial recognition and serial recall

The impact of the lexicality of memory items on memory performance was compared in two paradigms, serial recall and serial recognition. Experiments 1 to 3 tested 7- and 8-year-old children. Memory accuracy was only mildly impaired in lists containing nonwords compared with words in a serial recognition task involving judgements of whether the items in two sequences were in the same order (Experiment 1), although a substantial advantage for word over nonword items from the same stimulus pool was found in serial recall (Experiment 2). A stronger influence of lexicality on serial recall than serial recognition was further demonstrated in Experiments 3A and 3B, and in 4A and 4B using adult participants. These experiments also established comparable degrees of sensitivity to the phonological similarity of the memory sequences in the two paradigms. The phonological similarity effect in serial recall was found to arise from increased phoneme order errors, whereas the lexicality effect was due principally to the greater frequency of phoneme identity errors for nonwords. It is proposed that the lexicality effect originates in the redintegration of item information just prior to recall, and that this process is largely bypassed in serial recognition.     

Metacognition and learning about primacy and recency effects in free recall: The utilization of intrinsic and extrinsic cues when making judgments of learning

Although memory researchers know about primacy and recency effects, it is unclear whether students are aware of these effects and incorporate them when making judgments of learning (JOLs). The present research examined how participants use serial position information (extrinsic cues) when making JOLs after studying each item and showed that participants rely on the intrinsic qualities of the items and underestimate primacy and recency effects. However, when participants made JOLs prior to studying each item and engaged in multiple study-test sessions, their JOLs accurately reflected recall, as well as when serial position information was explicitly provided during the study phase. The findings are interpreted in a cue utilization framework and suggest that under certain conditions, participants can predict primacy and recency effects.     

Changing the tune: the structure of the input affects infants' use of absolute and relative pitch

Sequences of notes contain several different types of pitch cues, including both absolute and relative pitch information. What factors determine which of these cues are used when learning about tone sequences? Previous research suggests that infants tend to preferentially process absolute pitch patterns in continuous tone sequences, while other types of input elicit relative pitch use by infants. In order to ask whether the structure of the input influences infants’ choice of pitch cues, we presented learners with continuous tone streams in which absolute pitch cues were rendered uninformative by transposing the tone sequences. Under these circumstances, both infants and adults successfully tracked relative pitches in a statistical learning task. Implications for the role played by the structure of the input in the learning process are considered.     

Effects of contextual cues in recall and recognition memory: The misinformation effect reconsidered

Research in semantic word list‐learning paradigms suggests that presentation modality during encoding may influence word recognition at test. Given these findings, it is argued that some previous misinformation effect research might contain methodologies which are problematic. Misleading information groups typically receive erroneous information in written narratives, which may be further impeded by written tests. Results may therefore be explained by misinformation or encoding specificity. In two experiments, participants received restated, neutral, and misleading post‐event information through auditory or written modalities. Participants' recognition and recall of critical details about the source event were tested. In a recognition test using the standard testing procedure, there were no condition differences for post‐event information presented via an auditory modality. However, for post‐event information presented in the text modality, recognition performance was more accurate for restated information relative to neutral information, which in‐turn was better than the misled condition. Using the modified testing procedure, the differences were again limited to the text condition. Better performance was evident in the restated condition relative to the average of the neutral and the misled conditions, and there was no difference in performance between the neutral and the misled conditions. Using a recall test, however, there was no effect of modality. Memory was significantly better for restated information than for the average of the neutral and the misled conditions and poorer in the misled condition relative to the neutral condition. Results are discussed in terms of the effects of contextual cues at test, and methodological and interpretational limitations associated with previous research.